Attempt to guarantee a uniform distribution

Based on https://github.com/bluezio/xeger/blob/3098732bc920194a5bf5378310d24dc32f1e6cf2/src/main/java/nl/flotsam/xeger/Xeger.java#L106-L110

Src/Fare/Xeger.cs

@@ -83,10 +83,9 @@ public string Generate()
         /// <param name="random">The object used as the randomizer.</param>
         /// <returns>A random number in the given range.</returns>
         private static int GetRandomInt(int min, int max, Random random)
-        {
-            int dif = max - min;
-            double number = random.NextDouble();
-            return min + (int)Math.Round(number * dif);
+        {
+            int maxForRandom = max - min + 1;
+            return random.Next(maxForRandom) + min;
         }
 
         private void Generate(StringBuilder builder, State state)